Add refcnting to SkClipStack on SkCanvas

include/core/SkClipStack.h

Index: include/core/SkClipStack.h
diff --git a/include/core/SkClipStack.h b/include/core/SkClipStack.h
index 79789dcc268d80ad3c3b62bdd436063d5d2e45a0..8ef58335935eb89b1d63fa3e7e06e2fa4be6efc0 100644
--- a/include/core/SkClipStack.h
+++ b/include/core/SkClipStack.h
@@ -24,7 +24,7 @@ class SkCanvasClipVisitor;
 // (i.e., the fSaveCount in force when it was added). Restores are thus
 // implemented by removing clips from fDeque that have an fSaveCount larger
 // then the freshly decremented count.
-class SK_API SkClipStack {
+class SK_API SkClipStack : public SkRefCnt {

[mtklein, 2015/02/04 19:47:49]

If this sticks, SkNVRefCnt<SkClipStack> is a little cheaper to use as a base
class here

[bsalomon, 2015/02/05 15:51:32]

let's do it!

 public:
     enum BoundsType {
         // The bounding box contains all the pixels that can be written to